Serpentine heat exchangers commonly comprise a bundle of tubes of hairpin shape, also referred to herein as U-tubes, which are connected together by means of tubular junction pieces and which pass through a multiplicity of parallel cooling fins. The stack of cooling fins is fitted with at least one end plate, through which the hairpin shaped tubes pass. In heat exchangers of that type, at least one of the U-tubes has an end portion which extends beyond the end plate for connection to the fluid flow inlet or outlet pipe.
The end plate generally has a flat central portion, or central strap portion, which extends parallel to the cooling fins and which has two side flanges which extend either towards, and beside, the cooling fins, or else away from the cooling fins. This end plate essentially serves to hold the heat exchanger together, and/or as a means to which accessories can be fixed, for example a lug for supporting the flow pipe. In known heat exchangers of this type, the tubular junction pieces are ultrasonically brazed or swaged on to the end portions of the U-tubes.
Most heat exchangers of this kind have two serpentine tubes connected in parallel, with the fluid flow inlet or outlet pipe then being connected to the respective ends of the two serpentine tubes of the bundle. The flow pipe then comprises three parts which are pre-assembled by brazing, namely a threaded connector, an intermediate tube, and two secondary tubes which are connected respectively to the two serpentine tubes of the bundle. The connection of the two secondary tubes to the two tubes of the bundle is carried out either by brazing, or else by means of special swaging rings. Such a connection is complicated to make, even in the case in which the flow pipe is joined to only one of the serpentine tubes of the bundle. In addition, the flow pipe can only extend away from the heat exchanger along the axis of the heat exchanger tubes.